The use of sodium tripolyphosphate in food enhancement processes and compositions is well documented in the literature. Moisture preservation in meats and seafood is a typical benefit in the use of sodium tripolyphosphate. It is desirable to include sodium tripolyphosphate in such food treatment compositions as brine solutions containing sodium chloride(salt) as well as in blends incorporating spices, flavorings and salt. The sodium tripolyphosphate usually prepared has been found to provide a rate of solution in such compositions containing salt or spices/flavoring/salt such that it slows preparation or production time and can even result in solutions having a cloudy appearance indicating some suspended insolubles. In addition sediment may form which would interfere with meat treatment processes.
Typical examples of food processing wherein sodium tripolyphosphate is employed can be found in the patent literature. For example, U.S. Pat. No. 4,394,396 to Shimp et al. discloses a process for treating shrimp that results in their having desirable moisture and natural appearance. The treating solution contains sodium tripolyphosphate and sodium acid pyrophosphate salts in water wherein the salts have a weight ratio of 80:20 to 60:40 with an optional portion of "ordinary" salt up to about 7%. The patent indicates that if only sodium tripolyphosphate is employed there is provided an adequate degree of water retention but that the appearance of the treated shrimp is undesirable.
A typical brine solution is described in U.S. Pat. No. 5,164,213 to Bonkowski. The inventive brine mix described in that patent enables the user to add the ingredients of the brine in one step rather than the prior practice of adding ingredients stepwise with large amounts of water to obtain hydration or solution. The brine mix also contained various proteins, carbohydrates, hydrocolloids, salt, flavoring and phosphates into a single unit.
A typical marinade is described in U.S. Pat. No. 4,942,047 to Buckholz, Jr., et al. The percent of salt (including phosphate), flavor composition and/or flavor precursor composition in water for the marinade composition is said to vary from about 20% up to about 40% by weight with a preferred range of from about 25% to about 35% by weight of the liquid marinade composition.
The industry has searched for suitable phosphate salts which would dissolve reasonably well into brine and other salt solutions. One such example is found in U.S. Pat. No. 4,948,621 to Schwartz which attempts to provide inorganic polyphosphates which will form a clear, stable solution suitable for injection into meat products. The composition comprises sodium tripolyphosphate and a long chain glassy phosphate in sufficient quantities to provide 92 to 85 parts by weight sodium tripolyphosphate and 8 to 15 parts by weight of long-chain glassy phosphate. The procedure described therein provided for first dissolving the polyphosphates in water and then adding salt and other ingredients to the phosphate salt solution. There is desired in some instances a mixture of sodium tripolyphosphate and sodium pyrophosphate for use in preparing both food and detergent use. The ability to provide various mixtures of sodium tripolyphosphate and other polyphosphate salts by varying the Na/P ratio in the mixture being calcined is explained in U.S. Pat. No. 4,671,949 to Bourgeois, et al. which is incorporated herein by reference. The patent indicates the Na/P ratio of 1.667.+-.0.01 provides a particularly pure sodium tripolyphosphate which lacks caking tendency upon solution in water. A particular process involving regulation of the calcining process is also discloses to achieve a more desirable sodium tripolyphosphate.
Mixtures of orthophosphates, particularly mono and disodium phosphates, dried to a granular solid, are employed to prepare various polyphosphate including sodium tripolyphosphate, sodium pyrophosphates and sodium metaphosphate. Blends of these polyphosphates can be prepared by mixing them or, more conveniently, they are co-produced in proportion. U.S. Pat. No. 4,798,712 to Peterson described forming a mixture of polyphosphate particles by varying the amount of alkali metal to phosphorus mole ratio in the range of from 5:3 to 6:3, flash-drying the solution and then calcining to produce a polyphosphate mixture. According to this patent, the process provides a polyphosphate mixture containing from about 75% to about 85% by weight sodium pyrophosphate and from about 15% to about 25% by weight of sodium tripolyphosphate by calcining dried orthophosphates at a temperature in the range of from about 350.degree. to about 550.degree. C.
Food grade sodium tripolyphosphate has varying rates of dissolution in aqueous mixtures and has a particular problem involving cake formation depending upon the nature of the sodium tripolyphosphate. The above noted patents, particularly U.S. Pat. No. 4,671,949 discloses that if sodium tripolyphosphate is dissolved in a medium which is not agitated or inadequately agitated, there is typically produced lumps which are difficult to dissolve or result in caking or hardening. Also, hydrated phase II sodium tripolyphosphate will result in virtually instantaneous total caking or hardening, whereas hydrated phase I sodium tripolyphosphate does not result in any caking or hardening. The patent claims a sodium tripolyphosphate product which contains from 15% to 60% phase I and a carefully controlled Na/P ration of 1.667.+-.0.01. Such a product is stated to not exhibit solidification or caking in a quiescent solvent medium. The above noted patent U.S. Pat. No. 4,948,621 deals with the solution problem of sodium tripolyphosphate by incorporating from 8 to 15 parts by weight of a glassy phosphate into admixture with the sodium tripolyphosphate. In above note U.S. Pat. No. 4,394,396, a blend of sodium tripolyphosphate with sodium acid pyrophosphate in water was employed to provide a treatment for shrimp which would provide good water retention while at the same time preserve good food appearance of the cooked shrimp. No mention was made in the patent regarding solution rates.
There is needed a sodium tripolyphosphate which can be readily dissolved in water which also contains dissolved materials including salt, sugar, spices and flavorings. While mixtures of sodium tripolyphosphate with other polyphosphates have been known in the art, there are limitations on the amount which can be included with sodium tripolyphosphate and marketed as such in the food phosphate business. Food grade sodium tripolyphosphate must contain at least 85% by weight sodium tripolyphosphate. It is inconvenient to blend sodium tripolyphosphate with other products to achieve an acceptable mixture for the purpose of achieving salt compatibility in solution. It is therefore desirable to produce sodium tripolyphosphate in a process providing a mixture of phosphates which can be sold in the food industry under the sodium tripolyphosphate label but still providing rapid solution rates in salt or brine mixtures or with blends of spices or other flavorings including salt. Such a mixture would be considered a salt compatible sodium tripolyphosphate.